As a reader discovered, Western Digital Store offers the factory-refurbished Western Digital 4TB My Book USB 3.0 External Hard Drive, model no. RWDBFJK0040HBK-NESN, for $109.99 with free shipping. That's $5 below our mention for a new unit from three weeks ago and the lowest total price we've seen. (It's a current low by $29 for a new one.) It features local and cloud backup and up to 5GB/s data transfer speeds.
A 6-month Western Digital warranty applies.